This invention relates to rotating memories and, more particularly, to improved means for centering removable recording media on and clamping it to the spindle of a disk drive.
Removable recording media has been successfully utilized in the magnetic rotating memory industry for many years. Indeed, media removability and transportability are generally recognized as being among the more significant advantages of so-called floppy and cartridge-type disk drives. Consequently, substantial effort and expense have been devoted to the development of self centering clamping mechanisms for securing removable recording media to the spindles of such disk drives. See, for example, Chou et al. U.S. Pat. No. 3,898,814, which issued Aug. 12, 1975 on a "Mechanism for Clamping and Driving a Flexible Disk."
The practical advantages of removable recording media are more or less the same for optical disk memories as for magnetic disk memories. However, the media centering spindle clamps that have been developed for magnetic memories are not suitable for optical memories, primarily because of the tighter tolerances on the axial positioning of the recording media in an optical memory and the unique structural characteristics of optical recording media.
A cylindrical spindle, such as employed on a conventional phonographic turntable, would allow the aforementioned axial tolerance requirements to be satisfied, but there would be unacceptable instability in the centering of the recording media because of the necessary clearance between the outside diameter of the spindle and the inside diameter of the disk-like recording media. A sliding or variable taper spindle also could be configured to be consistant with the axial tolerance requirements, but such a spindle would not stabilize the centering of the recording media. Moreover, neither a cylindrical spindle nor a sliding taper spindle would assist to any significant extent in counteracting the unwanted disk/spindle slippage which tends to occur while the spindle and disk are accelerating and if impact forces are applied to the drive during operation.